You presume everyone would be playing serve and volley in a field with players like today, for instance thinking players with the exact skill sets of Nadal and Djokovic, the same ones who Becker himself claims would be irrelevant in that era, would be his main rivals in even a serve and volley based era, which is a silly assumption. In an era of serve and volleyers Federer would be in alot more trouble relative to his current dominance in the baseline only era, as while they dont exist today in the past there were MANY players with both better serves and especialy better volleys than Federer. In the 90s alone Sampras, Becker, Stich, Krajicek (yes 1 slam wonder Krajicek of all people), were superior to Federer in both serving and volleying ability. Edberg and Rafter were much superior in volleying. Philipoussis and Ivanisevic superior in serving.

Djokovic and Nadal and skill sets are not words that should be used in one sentence (if it's meant to be a complimentary one). Becker could have gone on to say Federer would be on 40+ Slams if he was born a decade earlier. That's how much ahead he is in shotmaking and tennis intelligence as opposed to any of his peers. The surfaces are an unfortunate corcumstance we cannot circumnavigate but since Becker raised the subject (of a hypothetical comparison) I think it would have been a reasonable haul for the Swiss genius.